* C06PAF Example Program Text * Mark 19 Release. NAG Copyright 1999. * .. Parameters .. INTEGER NIN, NOUT PARAMETER (NIN=5,NOUT=6) INTEGER NMAX PARAMETER (NMAX=20) * .. Local Scalars .. INTEGER IFAIL, J, N, NJ * .. Local Arrays .. DOUBLE PRECISION WORK(3*NMAX+15), X(0:NMAX+1), XX(0:NMAX-1) * .. External Subroutines .. EXTERNAL C06PAF * .. Executable Statements .. WRITE (NOUT,*) 'C06PAF Example Program Results' * Skip heading in data file READ (NIN,*) 20 CONTINUE READ (NIN,*,END=120) N IF (N.GT.1 .AND. N.LE.NMAX) THEN DO 40 J = 0, N - 1 READ (NIN,*) X(J) XX(J) = X(J) 40 CONTINUE IFAIL = 0 * CALL C06PAF('F',X,N,WORK,IFAIL) * WRITE (NOUT,*) WRITE (NOUT,*) 'Components of discrete Fourier transform' WRITE (NOUT,*) WRITE (NOUT,*) ' Real Imag' WRITE (NOUT,*) DO 60 J = 0, N/2 WRITE (NOUT,99999) J, X(2*J), X(2*J+1) 60 CONTINUE DO 80 J = N/2 + 1, N - 1 NJ = N - J WRITE (NOUT,99999) J, X(2*NJ), -X(2*NJ+1) 80 CONTINUE * CALL C06PAF('B',X,N,WORK,IFAIL) * WRITE (NOUT,*) WRITE (NOUT,*) + 'Original sequence as restored by inverse transform' WRITE (NOUT,*) WRITE (NOUT,*) ' Original Restored' WRITE (NOUT,*) DO 100 J = 0, N - 1 WRITE (NOUT,99999) J, XX(J), X(J) 100 CONTINUE GO TO 20 ELSE WRITE (NOUT,*) 'Invalid value of N' END IF 120 CONTINUE STOP * 99999 FORMAT (1X,I5,2F10.5) END